RU2051090C1 - Method for production of carbon-containing mass for production of graphitized articles - Google Patents

Abstract

FIELD: manufacturing of semiconductor devices. SUBSTANCE: calcined coke ground to size (-2.0-0) mm is fed into mixer, its quantity being 60-65 of total amount. Then it is heated to 110 C, poured with melted pitch (its quantity being 90 of total pitch mass) and mixed. The process is followed by adding natural graphite (its quantity being 7-10 of total amount) and pitch residue. Specific resistance of articles which are manufactured of said mass is 8-90 8-9 m/mm²,, their compressive strength being 54-56 MPa. EFFECT: improves efficiency of method. 1 tbl

Description

 The invention relates to the production of graphitized products and can be used in the electrode industry for the manufacture of heaters, crucibles, products of special-purpose materials (highly pure graphite) for semiconductor technology.

Closest to the invention is a method of preparing a carbon-containing mass to obtain carbon products, according to which natural graphite is used in an amount of 0.8-2.0 wt. [1]
However, in this method, the components of the filler charge are mixed with each other and then with a binder, which does not increase the uniformity of the structure and, as a result, increase the yield of products during heat treatment operations. The percentage of natural graphite in the mixture is not enough for a deeper decrease in electrical resistivity.

 The purpose of the invention is the stabilization and reduction of the electrical resistivity of graphite and increasing the yield of workpieces during heat treatment (firing and graphitization).

 In the production of graphitized products, the problem arises of increasing the yield of billets within, especially after firing and graphitization. This problem is solved by increasing the uniformity of the structure of the carbon-containing mass. The addition of natural graphite also solves the problem of stabilization and reduction of electrical resistivity.

 The invention establishes a certain order of mixing the components and increases the content of natural graphite to 7-10 wt. Together, these two points create a technical result. This is explained as follows: preliminary mixing of coke with a binder ensures equalization of the group composition of the binder on the surface of coke grains, helps to relieve internal stresses in the workpiece during the firing process, increases the mass of natural graphite to 7-10 wt. increases the thermal conductivity of green blanks, due to which cracking in firing and graphitization is reduced.

 In addition, natural graphite improves the conditions in graphitization, as a result of which the electrical resistivity of graphite decreases.

PRI me R 1. Coke-graphite-pitch composition consists of petroleum coke brand KNPS GOST 22898-78, calcined to 1275 ^about With a true density of 2.04-2.08 g / cm ³ , graphite natural (natural) GOST 7478-75, medium-temperature coal tar pitch grade "A", GOST 10200-86. The calcined coke is ground to a fraction of (-0.2-0) mm. A fraction (-0.2-2) mm is obtained in a ball mill with pneumatic separation of the material. The resulting fraction of coke in the amount of 65 wt. metered into a mixing machine, heated steam capacity of 2000 liters and heated with stirring for 20 min, and the coke temperature reaches 110 ° ^C. Then pour melted to ¹²⁰ ° C coal tar pitch in an amount of 90% of the required total amount, i.e. 25 wt . and mixed for 20 minutes, while the temperature of the mass rises to 145 ^about C.

The total preparation time of the composition is 80 minutes The resulting coke-graphite-pitch mass is crushed, and then grinded in a ball mill. The content of the fraction of 0.09 mm is 57 wt. The obtained press powder is pressed into a closed matrix at a specific pressure of 400 kgf / cm ² into billets with a diameter of 230 mm and a height of 300 mm. "Green" preform is charged in a metal box sized 1,3h1,3h1,3 m, poured suction carbon fraction (4-0) mm and fired in a furnace, a gas-heated to 1200 ^C for 330 hours. After unloading preforms from their furnace sorted out in order to determine the number of blanks with cracks and determine the yield of blanks. The yield of billets is shown in the table. The fired preform was impregnated with coal tar pitch, and re-graphitizable calcined in an electric resistance furnace at 2500 ^C for 40 hours using a perchloric purification.

 The table shows the electrical characteristics of the obtained graphite and the yield of billets after firing and graphitization.

 In examples 1-3 observe the mixing order and the content of natural graphite in the range of 7-10 wt. In examples 4-5, the usual mixing order is used: first, the mixture is mixed without a binder, then with a binder. As can be seen from the table, with the content of natural graphite 15 wt. the yield of billets is high, and the electrical resistivity is low, but the strength characteristics are deteriorating, which is unacceptable.

 As can be seen from the table, the invention allows to reduce the electrical resistivity of graphite by 11-25% to increase the yield of billets after heat treatment by 20%

Claims (1)

 METHOD FOR PREPARING A CARBON-CONTAINING MASS FOR PRODUCING GRAPHITE PRODUCTS, including crushing coke, grinding it to a fine-grained fraction, mixing with pitch, characterized in that first coke is mixed with 90% of the entire pitch, then the natural amount is added and the mixture is dosed and mixed subsequent stirring, and the ratio of components in the specified mass is selected as follows, wt. Calcined coke fraction 0.2 ^o C 0 mm 60 65
Natural graphite 7 10
Coal tar Rest

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